This is about the ability to complete a project fast, which is typically about both convenience of fast prototyping, and performance (ie. you don't want to wait days for the results to be computed before changing something in the code, and you want that change to be easy).
And probably few buyers who want fast cars care about aerodynamic design per se -- they care about speed; sure, if better aerodynamics is what's necessary then so be it, but they would also prefer a fast car with poor aerodynamics and a huge engine to the very aerodynamic and fuel efficient, but slow one.
As is usually the case with language design, performance and optimization are often on the opposite side of the scale from code learn-ability and usability. More than likely, the "huge engine" would be some other burden the language has that he doesn't want in exchange for faster prototyping.
I'd actually say both Julia and Matlab are often quite decent on both learnability, usability (at least for their purpose -- especially as the library for Julia develops), and performance. Certainly, on par with other newly-designed languages. Sure, you can go faster with Fortran, but you can do that when you see that it is really needed...
And probably few buyers who want fast cars care about aerodynamic design per se -- they care about speed; sure, if better aerodynamics is what's necessary then so be it, but they would also prefer a fast car with poor aerodynamics and a huge engine to the very aerodynamic and fuel efficient, but slow one.